Why VIEW-AS ALERT BOX not working in Linux side?

I have written a program for finding non sequence orders while scanning and if the non sequence work order found then this will pop up one small window and alert user for whether accept or reject for further scanning. The issue here is this program is working in window server very well but not showing pop window in linux side. Let me share the program.

DEFINE VARIABLE OERROR AS CHARACTER NO-UNDO.
DEFINE VARIABLE lpc_valid AS LOGICAL NO-UNDO.
DEFINE VARIABLE opi_ExpectedSeq AS CHARACTER NO-UNDO.
DEFINE VARIABLE iCurrentSeq AS INTEGER NO-UNDO.
DEFINE VARIABLE iPrevscandSeq AS INTEGER NO-UNDO.
DEFINE VARIABLE cMessageTxt AS CHARACTER NO-UNDO.

ASSIGN
iPrevscandSeq = 20
iCurrentSeq = 22.


IF iCurrentSeq NE (iPrevscandSeq + 1) THEN DO:

cMessageTxt = "Current WO Seq : " + STRING(iCurrentSeq) + " EXPECTED SEQ : " + STRING(iPrevscandSeq + 1).

MESSAGE cMessageTxt
VIEW-AS ALERT-BOX QUESTION BUTTONS YES-NO-CANCEL
TITLE 'Wrong WO Seq'UPDATE lChoice AS LOGICAL.

CASE lChoice:
WHEN FALSE THEN DO:
ASSIGN
OERROR = "User Rejected For Non Sequence WO- Current Seq -"
lpc_valid = FALSE.
END.
END.
END.


/* The data is retriving from the databases which is running in linux and window sever side also.
The program that you are seeing now is calling by window application which is also running in linux side */


I don't know what is the issue here. Please help me to fix this

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